1. Field of the Invention
The invention relates to a ringlift crane.
2. Discussion of the Prior Art
A known ringlift crane is described in the Mannesmann Demag Baumaschinen company brochure entitled xe2x80x9cRinglift Cranesxe2x80x9d CC 2000 RL; CC 4000 RL, issue November 1982. This ringlift crane has a ring which can be elevated, forms an annular track and comprises a plurality of segments which can be connected to one another. Arranged within the ring is an undercarriage and an upper carriage, which is connected for slewing action thereto and has a plurality of hoisting winches. In the two end regions, the upper carriage is connected to in each case one adapter, and these adapters are supported with rolling action on the annular track of the ring by means of sets of rollers which are arranged on the adapters and are connected to one another via links. In this case, the center point of the ring and/or of the undercarriage forms the slewing axis. One adapter is designed for accommodating a counterweight and the other adapter is designed as a load-bearing element for a boom which can be articulated at the free end of the adapter. The slewing movement of the ringlift crane is produced by means of a toothed rim, which is arranged on the inside of the ring, and pinions which engage in the rim and are mounted via links. For the purpose of stabilizing the overall structure, the undercarriage is connected to different sections of the ring via reinforcing struts.
A comparable design is known from U.S. Pat. No. 4,103,783. This ringlift crane comprises a ring, which can be elevated and forms an annular track, and a structure within the ring with a kingpin and a platform which is provided with a sleeve for accommodating the kingpin. In the two end regions, the platform is connected to in each case one adapters. The adapters are supported with rolling action on the ring by means of sets of rollers arranged on the adapters. The center point of the ring forms the slewing axis for the platform. A plurality of hoisting winches are arranged on the platform and a counterweight is arranged on the rear adapter. A main boom and a mast (counter-boom) are articulated on the front adapter. The single-part ring is stiffened by struts which run within the ring in secant form. In each case one piston/cylinder unit is arranged at four points of the circumference, at the ends of two mutually parallel struts, it being possible for a supporting foot to be arranged at the free end of the piston/cylinder unit. By means of these four piston/cylinder units, it is possible for the ring to be raised together with the crane arranged thereon, with the result that a crawler-type vehicle or the like can be moved therebeneath. The crawler-type vehicle can be locked to the load-bearing element. Travel of the ringlift crane as a whole is possible in this way.
The disadvantage with the last-mentioned design is that the size of the ring diameter, and thus the maximum load which can be borne, is limited. Moreover, the way in which the ringlift crane is connected to the transporting unit is complicated. Furthermore, the non-divided ring requires a large amount of space during travel of the ringlift crane and, depending on the local conditions at the use location, this amount of space is not always available.
A ringlift crane of the generic type is known from U.S. Pat. No. 4,196,816. This ringlift crane comprises a ring which can be elevated, forms an annular track and has a plurality of segments which can be connected to one another, there being arranged within said ring an undercarriage which has an upper carriage, which is connected for slewing action to the undercarriage and has a plurality of hoisting winches, and two trusses which are spaced apart parallel to one another and are provided, in two mutually opposite end regions, with in each case one adapter and can be bolted to, and unbolted from, the upper carriage via crossmembers. The adapters are supported with rolling action on the annular track of the ring by means of rollers arranged on the adapters, it being the case that the center point of the ring and/or of the undercarriage forms the slewing axis. One adapter is designed for accommodating a counterweight and the other adapter is designed for accommodating a boom which may be articulated. A toothed rim is arranged for producing the slewing movement of the ringlift crane, the slewing movement thereof being transmitted to the two trusses. The undercarriage is connected to different sections of the ring via reinforcing struts.
The disadvantage here is that, during pivoting and traveling, the components of the crane are supported on the ring and thus on the undercarriage. On account of the power of the crawler-type vehicles being too low, first of all counterweight reductions have to be carried out for traveling and pivoting. Since the counterweight cannot be displaced, further dismantling operations (e.g. boom parts) are necessary for balancing out the crane. In order that the crane can pivot or travel, it has to be raised up on the ring and the supporting plates either have to be removed completely or all have to be raised upward individually.
The object of the invention is to provide a ringlift crane which can easily be pivoted and made to travel in a space-saving manner and without counterweight reductions and without parts being dismantled. Moreover, the intention is for it to be possible to use as many components as possible in a modular manner for different ringlift classes.
The invention proposes that, for the purpose of setting different modes of operation of the crane, the trusses can be raised relative to the basic machine and connected in different ways to the crossmembers with a force fit, it being the case that, in the starting position, the form-fitting connection between the trusses and the crossmembers has a predeterminable level of play. For the stewing movement a plurality of ring trolleys are provided which are of identical construction, have two axles and wheels fastened thereon and can be connected with a form fit, on the one hand, to the trusses and, on the other hand, to the ring or a ring segment. At least one axle of the ring trolleys arranged beneath the boom and/or beneath the counterweight can be driven. It is thus possible to dispense with the hitherto conventional toothed rim and the high-outlay pinion drive. In order to realize the force fitting connection between the truss and the crossmember, an upright bolt having a stop is arranged in each end region of each crossmember. If there are two crossmembers, this means four bolts. The stop, which preferably comprises a round plate, interacts with a bearing block which encloses the bolt and is fastened on the truss. The spacing between the top side of the crossmember and the plate of the bolt, on the one hand, and the spacing between the base plate of the bearing block and the stop of the bolt, on the other hand, can be partially or more or less completely filled by spacer plates which can be displaced on the top side of the crossmember. The spacer plates can be bolted and unbolted via carry-along pins.
Depending on the size of the ring, each truss comprises sections which are suitable for normal road transport and can be bolted to one another and unbolted from one another. Unlike the known prior art, the four piston/cylinder units, which are necessary for raising the overall structure, are arranged in the end region of the trusses. Preferably fastened on each end side of each truss is an angle piece, which, at its free end, can be connected to the piston/cylinder unit. As is known, a supporting foot can be arranged at the free end of the piston. The operation of raising the overall structure by means of the four piston/cylinder units allows the force fitting connection between the crossmembers and the two trusses. This easily ensures the capacity of the ringlift crane for pivoting and traveling.
The different ways of providing a force fitting connection between the trusses and the crossmembers on the upper carriage fulfill three functions:
Pivot locking
Since, with the high loads, the basic machine can no longer pivot straight away into another direction of travel, the proposed locking system is utilized as an auxiliary means. The basic crane and ring are raised with the aid of the piston/cylinder units fastened at the ends of the trusses, a force fitting connection having been produced beforehand between the crossmembers and the trusses by means of displaceable spacer plates, with the result that the crossmembers, and thus the upper carriage, are raised as well. With the aid of the slewing gear on the upper carriage, the undercarriage is then pivoted into the desired direction of travel together with the ring.
Travel locking
With this type of locking, the trusses and the ring are raised by means of the four piston/cylinder units fastened at the ends of the trusses and, following force fitting connection between the non-raised crossmembers and the trusses by means of push-in spacer plates, the undercarriage can travel in a straight linexe2x80x94to be precise forward and backward.
Operational locking
By virtue of the locking system, it is also possible to use the ring, the trusses and the basic machine as an additional counterweight during the operation of the crane. This cuts back, in some circumstances, on up to 10% of the counterweight and the associated transport.
Since the ring comprises, as is known, a plurality of segments which can be connected to one another, it is possible, in a space-saving manner, for a plurality of segments to be dismantled prior to the travel of the crane. Two mutually opposite segments can be locked to the trusses via the ring trolleys and can travel along with the crane. In this case, the tangential extent of the lockable segments corresponds at most to the widthwise extent of the counterweight.
In order for it to be possible for the maximum load to be increased further, it is proposed, furthermore, to allow the ring trolleys to be supported on two concentric rings, with the result that the Hertzian stress for the wheels which are in contact with the ring surface remains below the permissible maximum value. The total load is thus often divided in half between two rings. In order for it to be possible for the ring trolleys to be displaced in the circumferential direction of the two rings, in each case two mutually opposite trolleys are connected to one another via a connecting link. Two trolleys arranged on the inner ring and two trolleys arranged on the outer ring form a unit and form the minimum number of components for setting up a trolley. Such a unit and a further unit of the same type can be connected to one another via a bridge element. The trolleys are linked to one another by a plug-in connection. The maximum number of ring trolleys which can be arranged on a ring is equal to or smaller than the arc length of the individual ring segment divided by the length of the ring trolleys. The angle taken up by the ring segment is preferably 60 degrees. The ring trolleys are of identical construction and are suitable for a ring with a small diameter, for example, of 21 meters and for a ring with a large diameter, for example, of 32 meters. This is realized such that the angle enclosed by the intersecting center lines of the two axles is the average between the angle for the smallest ring diameter and the angle for the largest ring diameter. The resulting negative effects on the rolling behavior of the ring trolleys in the case of a ring diameter which differs from the average are consciously accepted. The different rolling path of the wheel rolling on the outer region of the ring in relation to the wheel rolling on the inner region is compensated for by a different diameter. In order, however, that the ring trolleys continue to be horizontal, the ring track is subdivided into an outer track and an inner track with a step located therebetween, of which the height corresponds to half the difference between the wheel diameters. The form-fitting connection between ring trolley and ring or ring segment takes place via supporting plates which are arranged on the ring trolley and, at the end, are provided with a hook roller. The hook rollers engage beneath the top flange of the ring and thus limit a raising-up movement of the ring trolleys.
The center-of-gravity position of the ringlift crane is determined, inter alia, quite basically by the positioning of the counterweight in relation to the basic machine. In order to change this center-of-gravity position, it is thus proposed to arrange counterweight trolleys beneath the platform for the counterweight, it being possible for the wheels of the counterweight trolleys to roll on the top side of the trusses. In the same way, it is also proposed to arrange at that end of the two trusses which is located in the region of the counterweight an extension of the trusses that extends beyond the ring. The two measures have the following advantages: the counterweight can be displaced by means of the counterweight trolleys from the normal operating position in the direction of the slewing center. This optimizes the center of gravity for the travel of the ringlift crane on site. During travel of the counterweight along the extension beyond the ring, the following advantages are produced: with the same counterweight, a larger counterweight moment is produced, and this can be utilized for a higher load-bearing capacity. With the same counterweight moment, the counterweight can be reduced and the transportation of counterweight elements is reduced to the same extent.
The advantage of the proposed ringlift crane can be seen in that, despite a large increase in the load moments which can be borne, the Hertzian stress in the wheel surface annular track contact region remains beneath the permissible values and, without the actual crane being dismantled, the ringlift crane remains in a state in which it can travel easily, and the amount of space required for this travel is no larger than the widthwise extent of the counterweight.
Furthermore, in the proposed design, importance has been placed on the ringlift crane being of modular construction and on as many standardized components being used as possible. This begins with the undercarriage and the upper carriage, which are constituent parts of a standard crane, and is continued via the boom used and the hoisting winches as well as the crane cab. The boom may be designed as a single boom or as a so-called double boom. The last-mentioned structure has the advantage that the individual elements of the lower-crane-class double boom can be transported more easily, and can transmit a higher load moment, than the single boom used from a higher crane class. The trusses, which comprise a plurality of sections, can be used for a single ring and for a double ring. The ring trolleys are standardized and, depending on the load which is to be transmitted, the number of ring trolleys is increased or reduced and correspondingly linked to one another. In order to simplify the assembling and dismantling operations, wherever possible, use is made of plug-in connections, with the result that individual components can be raised and plugged in by means of an auxiliary crane.